Ford RM-91Blue Scout Junior

The XRM-91Blue Scout Junior (sometimes called Journeyman B) was a rocket of the U.S. Air Force's System 609A
Blue Scout family (for general information on Blue Scout, see article on RM-89 Blue Scout I).
The XRM-91 did not resemble the other Scout variants externally, because the usual first Scout stage (an Aerojet General
Algol) was not used. Instead, the four-stage Blue Scout Junior used Scout's 2nd and 3rd stages (Castor and
Antares) as the first two stages, and added an Aerojet General Alcor and a spherical NOTS Cetus in a common nose
fairing. The XRM-91 also lacked the gyro-stabilization and guidance system of the RM-89 Blue Scout I
and RM-90 Blue Scout II, making it a completely unguided rocket. It relied on second-stage fins and two
spin motors to achieve a stable flight trajectory.

Photo: USAF

XRM-91

The first launch of an XRM-91 occurred on 21 September 1960, making it actually the first Blue Scout configuration to fly.
The flight was planned to make radiation and magnetic field measurements at distances of up to 26700 km (16600 miles) from earth,
and while the rocket did indeed achieve this altitude, the telemetry system failed so that no data was received. The second launch
in November ended with a failure during second stage burn. The third flight was to measure particle densities in the Van Allen belts
and reached a distance of 225000 km (140000 miles), but again a telemetry failure prevented the reception of scientific data.
The fourth and final XRM-91 mission in December 1961 also carried particle detectors, and was the only completely successful flight
of the initial Blue Scout Junior program. The Blue Scout Junior would have been easily powerful enough to put a small
satellite in low-earth orbit but was never used to do so.

Photo: USAF

XRM-91

The Blue Scout Junior was regarded by the USAF as the most useful of the various Blue Scout configurations. It was used
between between 1962 and 1965 by the Air Force to launch suborbital scientific payloads to very high altitudes. The
SLV-1B* was effectively identical to the XRM-91, and was launched seven times between July 1963 and June 1965
with magnetospheric experiments as payload. The LV-1B (also known as SLV-1B(m)) was a three-stage variant which omitted the
Cetus 4th stage of XRM-91/SLV-1B. The USAF lauchned three LV-1Bs between November 1962 and December 1964 on ion engine test missions.
The SLV-1C was another three stage rocket, which replaced the LV-1B's Alcor third stage by an Altair.
It was used as the rocket for the MER-6A interim ERCS (Emergency Rocket Communications System) vehicle.
The NASA used a three-stage Blue Scout Junior configuration (using the same stages as the LV-1B) as the RAM B.